1. Field of the Invention
The present invention relates to an ejector cycle device having an ejector, which is used for decompressing a fluid while being used as a kinetic pump for transmitting a fluid by entrainment function of a driving fluid jetted at a high speed. For example, the ejector cycle device can be suitably used as a refrigerant cycle for cooling plural different-temperature cooling subjects.
2. Description of Related Art
A vapor-compression refrigerant cycle device (ejector cycle device) having an ejector 62 is described in JP Patent No. 3322263 (corresponding to U.S. Pat. Nos. 6,477,857 and 6,574,987). The ejector cycle device includes a compressor 60, a refrigerant radiator 61, the ejector 62, first and second evaporators 63, 64 and a gas-liquid separator 65. The first evaporator 63 is located between a refrigerant discharge side of the ejector 62 and the gas-liquid separator 65, and the second evaporator 64 is located between a refrigerant suction port of the ejector 62 and a refrigerant outlet of the gas-liquid separator 65.
In this ejector cycle device, a throttle open degree of a nozzle portion of the ejector 62 is controlled, so that refrigerant at an outlet side of the first evaporator 63 becomes in a gas-liquid two-phase state while a cooling capacity of the second evaporator 64 is controlled. In this case, the cooling capacity of the first evaporator 63 is operatively linked with the cooling capacity of the second evaporator 64, and it is difficult to suitably control the cooling capacities of both the first and second evaporators 61, 62.
In addition, when the temperature of refrigerant in one of the evaporators 63, 64 is reduced to a temperature lower than 0° C., moisture contained in air is frozen on the one evaporator. The flow of refrigerant to the one evaporator may be stopped for performing a defrosting operation of the one evaporator. However, in this ejector cycle device, both of the flow of refrigerant to the first evaporator 63 and the flow of refrigerant to the second evaporator 64 need to be stopped.